JPH0242648B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Thermoplastically processed substantially linear polyester-polyols consisting of aliphatic dicarboxylic acids and alkylene glycols, hydroxycarboxylic acids, or polyether-polyols based on polytetrahydrofuran. Possible polyurethane elastomers are known. An overview of polyurethane-elastomers of this type can be found, for example, in “Wrethanes in Elastomers and Coatings”.
Coatings)” Technomic Publishing Co., Ltd.
Publishing Company) 265W. State Street, West Haught, CT/USA
1973, pp. 201-230 or “Kunstschutsuf.”
``Kunststoff-Handbuch'', Volume 1 by R. Vieweg and H. Ho¨chtlen, ``Polyurethane'' by Carl Hanser.
(Hanser) Publisher, Milunchen, 1966, pages 260 onwards.

Furthermore, a dense pore-free outer skin and foam core,
Processes for producing polyurethane foams having a so-called integral foam structure are also known. The basics, processing and applications of this type of foam can be found, for example, in the monograph "Integralschaumstoffe" by H. Piechota and H. Ro¨hr, published by Karl Hanser Verlag. , Miyunchen, Vienna, 1975.

German Patent Application Publication No. 1694138 discloses that an organic polyisocyanate and a compound having a large number of reactive hydrogen atoms are used as a blowing agent in a low-boiling point solvent, and the above hydrogen atom-containing compound 100 is used as a blowing agent.
A method is described for producing rigid polyurethane integral foams by reaction in the presence of up to 0.2 mol/g of 1.45 to 8.15, the product of the corresponding density and compression ratio is 0.2 to 1.2, and the foamable reaction mixture is poured into a mold having a surface temperature of at least 60° C. below the maximum reaction temperature. It is characterized by

Additionally, an overview of soft integral foams can be found in “Advances in Urethane Science and Technology.
Urethane Science Technology)” Volume 2, 1973
, pp. 203 onwards (Technomic Publication,
Technomic Publishing Co., 265W State St.
Westport Conn.06880).

“Rubber Age” 1966 5
The issue (pages 76-80) describes a method for producing microporous polyurethane rubber from an NCO group-containing prepolymer based on toluylene diisocyanate and polytetramethylene ether-glycol and a diamine as a chain extender. Are listed.

In the process, inert, low-boiling organic solvents are always used as blowing agents, since only then a dense shell is achieved. In contrast, diols and diamines are used as chain extenders.

To produce cellular elastomers, carbon dioxide formed during the reaction of diisocyanates with water, nitrogen from thermally unstable nitrogen compounds, and solvents are used as blowing agents [see above for "Kunstschütz"]. “Polyurethane” by R. Biebeck and A. Hechtlen in “Totsuf Handbutsho” Volume 276
page onwards]. In this case, the disadvantage is that the cellular elastomer foamed with carbon dioxide has essentially only open pores. If a closed-cell product containing carbon dioxide in the bubbles is formed, the product will already shrink considerably during production. Furthermore, the bubbles burst when subjected to dynamic loads, thus making the elastomer water-absorbing.

The object of the invention was to find a method for producing closed-cell polyurethane moldings which can be used in particular as elastic members capable of dynamic loading. Furthermore, the molded article should have a densified peripheral area. Furthermore, the molded article should exhibit a low water absorption capacity even after a large number of cyclic loads, ie more than 100,000 cyclic loads.

The above problem surprisingly relates to a method for producing a polyurethane molded article having a highly densified peripheral region and substantially closed cells by reacting an organic polyisocyanate, a polyol, and water. a) based on organic diisocyanates and substantially linear polyester-polyols or polytetramethylene ether-glycols,
100 parts by weight of an NCO group-containing prepolymer having an NCO content of 3 to 6% by weight and (b) 0.5 to 1.6 parts by weight of water, (c) at least one catalyst and (d) the presence of auxiliaries and optionally additives. Mix vigorously and reduce the resulting mixture to 50
It is characterized in that it is placed in a molding machine with a surface temperature of the inner walls of the mold of ~70° C., the molding machine is closed and the reaction mixture is cured under compression.

If a commercially available stabilized NCO group-containing prepolymer is mixed at 90°C with a mixture consisting of an emulsifier, a conventional amount of catalyst and water and the resulting foamable reaction mixture is poured into a room temperature mold where it hardens. , an open-pore pore structure is usually obtained in molded articles with low densities. The molded article thus produced, which can be used as an elastic member, and has a volume of 110 cm ³ and a density of 0.45 g/cm ³ absorbs about 60 g of water when compressed in water and decompressed.

Therefore, according to the method of the present invention, using water as a blowing agent, it is possible to obtain a molded article that substantially does not absorb water when compressed in water and subsequently depressurized, even though the volume and density are the same as described above. This was both surprising and unexpected. Dynamic loads, e.g.
Even after 100,000 cyclic loadings (70% compression and depressurization), no significant increase in absorption is observed. There was no deterioration of the elastic characteristic line due to freezing within the mold.

Starting materials that can be reacted according to the method of the invention to obtain molded articles with substantially closed cells and a densified peripheral area include:

Polyols for producing the NCO group-containing prepolymers are polytetramethylene ether glycols and preferably essentially linear polyester polyols, in particular with an OH number of 20 to 225, preferably 35 to 120. Polyester-diols are suitable. The polyester-polyols can be used as single component or in the form of mixtures.

Suitable substantially linear polyester-polyols can be prepared, for example, from dicarboxylic acids and dihydric alcohols having 2 to 12 carbon atoms. Dicarboxylic acids include, for example, aliphatic dicarboxylic acids such as succinic acid, glutaric acid, adipic acid, succinic acid, azelaic acid and sebacic acid and aromatic dicarboxylic acids such as phthalic acid, isophthalic acid and terephthalic acid. acid. The dicarboxylic acids can be used individually or as mixtures. To prepare the polyester-polyols, corresponding carboxylic acid derivatives, such as carboxylic esters, carboxylic anhydrides or carboxylic acid chlorides having 1 to 4 carbon atoms in the alcohol group, can optionally be used instead of the carboxylic acids. It may be advantageous to use . Examples of dihydric alcohols are glycols with 2 to 16 hydrocarbons, preferably 2 to 6 hydrocarbons, such as ethylene glycol, diethylene glycol,
Butanediol-1,4, pentanediol-
1,5, hexanediol-1,6, decanediol-1,10,2,2-dimethylpropanediol-1,3, propanediol-1,3 and dipropylene glycol. Depending on the desired properties in each case, the dihydric alcohols can be used alone or optionally mixed with one another. Furthermore, condensation products of hydroxyl group-containing polyesters, ω-hydroxylcarboxylic acids, of carbonic acid and the glycols mentioned above, especially those having 4 to 6 carbon atoms, such as butanediol-1,4 and/or hexanediol-1,6. and preferably polymerization products of lactones, such as optionally substituted ε-caprolactone.

Polyester-polyols include ethanediol-polyadipate, 1,4-butanediol-polyadipate, ethanediol-butanediol, polyadipate, 1,6-hexanediol-neopentyl glycol, polyadipate, 1,6-hexane. Preference is given to using diol-1,4-butanediol-polyadipate and polycaprolactone.

As organic polyisocyanates, preference is given to using aromatic diisocyanates. For example, 4,4'-diphenyl diisocyanate, 3,
3'-dimethyl-4,4'-diphenyl diisocyanate, p-phenylene diisocyanate, 2,
4-Toluylene diisocyanate, mixture of 2,4- and 2,6-toluylene diisocyanate, 4,4'-diphenylmethane diisocyanate, urethane-modified liquid 4,4'-diphenylmethane diisocyanate, 2,4' - and 4,4'-diphenylmethane diisocyanate and preferably 1,5-naphthylene-
Diisocyanates are mentioned.

To produce the NCO group-containing prepolymer (a),
organic diisocyanates and polyester-polyols or polytetramethylene ether-glycols at temperatures of 60 to 160°C, advantageously 90 to 150°C, especially 120 to
React at a temperature of 150°C. The reaction can optionally also be carried out in the presence of customary catalysts, such as tertiary amines and/or metal salts. The resulting NCO group-containing prepolymer has an NCO content of 3 to 6.
% by weight, preferably 3.5-4.5% by weight and a viscosity of about 2000-6000 mPas at 90°C, advantageously 2500-4500 mPas
has. The product is storage stable for a long time at room temperature with exclusion of moisture.

To produce cellular moldings, water is used exclusively as a blowing agent, in this case an NCO content of 3-6% by weight.
0.5 to 1.6 water per 100 parts by weight of prepolymer with
Parts by weight are used, preferably from 0.6 to 1.2 parts by weight, which corresponds to an NCO:OH group ratio of 0.8 to 1.3:1.

To accelerate the reaction between the NCO group-containing prepolymer and water, tertiary amines are preferably used as catalysts. In particular, for example dimethylcyclohexylamine, dimethylbenzylamine, N-methyl- or ethylmorpholine, N,N'-dimethyl-piperazine, pyridine, 1,2-dimethylimidazole, pentamethyl-diethylenetriamine, 1-methyl-4-dimethyl Mention may be made of aminoethyl-piperazine and diazabicyclo-(2,2,2)-octane. The amount of catalyst depends substantially on the reactivity of the components and the activity of the catalyst. This amount is advantageously selected such that no reaction occurs during the mixing step and during the time of pouring into the mold and the resulting molded article is hard enough to be demolded after 10 to 30 minutes of reaction. Catalyst per 100 parts by weight of NCO group-containing prepolymer
It has proven advantageous to use 0.01 to 2.0 parts by weight. Especially NCO group-containing prepolymer 100
Advantageously, 0.05 to 1.0 parts by weight are used.

Furthermore, the combined use of auxiliaries and/or additives has proven advantageous for producing closed-cell shaped articles. Examples include surface-active substances, foam regulators, flame retardants, hydrolytic protection agents, stabilizers against light, heat or discoloration, dyes, pigments, inorganic or organic fillers.

For example, surface-active substances which are suitable for assisting in the homogenization of the starting materials and, if appropriate, also for adjusting the cell structure of the cell-containing polyurethane elastomers, are suitable. Examples include siloxane-oxyalkylene copolymers and other organopolysiloxanes, oxyethylated alkylphenols, oxyethylated fatty alcohols, polyoxyethylene esters, paraffin oil, castor oil or ricinoleic acid esters and Turkish red oil. 0.01 to 2.0 parts by weight, preferably 0.1 to 2.0 parts by weight, per 100 parts by weight of NCO group-containing prepolymer.
Used in an amount of 1.0 part by weight. Preference is given to using siloxane-oxyalkylene copolymers.

Suitable flame retardants are, for example, tricresyl phosphate, tris-2-chloroethyl phosphate and tris-chloropropyl phosphate.

In addition to the halogen-substituted phosphates already mentioned, inorganic flame retardants such as red phosphorus, antimony trioxide, arsenic oxide, ammonium phosphate, calcium sulfate and melamine can be used for the flame retardant treatment of polyurethane elastomers. You can also do it. N.C.O.
Generally from 5 to 50 parts by weight, preferably from 5 to 25 parts by weight of said flame retardant per 100 parts by weight of the group-containing prepolymer.
It has proven advantageous to use parts by weight.

A detailed description of the other auxiliaries and additives mentioned can be found in the specialized literature, for example in the monographs JHSaunders and KCFrisch.
Author “High Polymers”, Vol.
Volume XII “Polyurethanes” Parts 1 and 2, Interscience
science) Publishers, 1962 and 1964.

To produce cellular moldings, the NCO group-containing prepolymer is heated to a temperature of about 60 to 120 °C, preferably 80 to 110 °C, and at this temperature the prepolymer is composed of water, catalyst and auxiliaries and optionally additives. Mix vigorously with the mixture. This reactive mixture is poured into a molding machine with a surface temperature of the inner mold walls of 50-70 °C, advantageously 55-65 °C, in an amount corresponding to the desired density of the molded article, the mold is closed and under compression. harden. The molded article obtained can be demolded after about 10 to 40 minutes.

As mold, a metal mold is preferably used, which mold is adjusted to a constant temperature. The heat of reaction generated thereby causes a slight heating of the mold surface at the beginning of curing, but this is rapidly compensated by the tempering medium.

The molded article manufactured according to the present invention has a total density of
250-800 g/, especially 300-500 g/.
This molded product has a substantially closed cell shape and a thickness of
It has a densified peripheral area of 0.1-3 mm and a density of about 500-1000 g/. Water absorption capacity is extremely low. This molded product does not show any bubble bursting in the surrounding area even after more than 100,000 cycles of loading. The molded part is advantageously used, for example, as an elastic member in a motor vehicle, in which case it additionally performs a protective function for the metal parts.

Next, the present invention will be explained in detail with reference to Examples. In addition,
"Parts" in Examples are "parts by weight."

Example 1 (a) Preparation of a prepolymer containing NCO groups 1000 parts of polyethylene glycol adipate with an OH value of 56 are dehydrated for 2 hours at 120° C. and 50 mbar in a stirred flask equipped with a stirrer, a thermometer and a vacuum connection. did. Subsequently, 240 parts of 1,5-naphthylene diisocyanate were added to the polyester polyol at 130 DEG C. with vigorous stirring, and the reaction was terminated at 130 DEG C. within 20 minutes.
It is then allowed to cool to 90°C over 1 hour.
1240 parts of a prepolymer containing NCO groups are obtained with an NCO content of 4.0% and a viscosity of 3800 mPas at 90°C.

(b) Production of molded articles To produce molded articles, 160 g of the prepolymer described under (a) with a temperature of 90°C are added to a temperature of 50°C.

It was mixed vigorously with 3.45 g of a mixture consisting of 1.4 parts of water, 0.05 parts of triethylenediamine, 1.4 parts of sodium salt of Turkish red oil, and 0.6 parts of Silicone Stabilizer 131 (manufactured by Dow Corning). After homogenization, the reactive mixture was poured into an aluminum mold with internal dimensions of 21.2 x 5.5 x 3.0 cm, with a mold surface temperature inside the mold of 60°C, and the mold was closed.
Molded articles that could be demolded after 30 minutes had the following mechanical property data:

Total density (g/) densified peripheral area 454 Thickness (mm) 2 Density (g/) 700 Core density (g/) 330 After 100,000 cyclic loads with 70% compression/release at 2Hz Water absorption amount (g) 5 Example 2 (a) Production of NCO group-containing polymer Polyethylene glycol having an OH value of 56/
1000 parts of butanediol-1,4 (1:1 mol)-adipate were dehydrated for 2 hours at 120 DEG C. and 50 mbar in a stirred flask equipped with a stirrer, thermometer and vacuum connection. Subsequently, the polyester polyol was heated to 126°C with vigorous stirring for 1.
250 parts of 5-naphthylene diisocyanate were added and the reaction was completed within 30 minutes at 128°C. Then, it was cooled to 86°C over 1 hour. N.C.O.
With content 4.25% and viscosity 3100mpas at 86℃
1250 parts of NCO group-containing prepolymer were obtained.

(b) Manufacture of the molded article To manufacture the molded article, 160 g of the prepolymer described in (a), having a temperature of 85° C., are mixed with 1.5 parts of water, 0.05 part of pentamethyl-diethylenetriamine, having a temperature of 55° C. ) ON 50D (BASF
4.05 g of a mixture consisting of 1.5 parts of silicone stabilizer B 840 (Fa. Goldschmidt) were mixed vigorously. After homogenization, the reactive mixture was poured into an aluminum mold with internal dimensions of 21.2 x 1.5 x 3.0 cm, with a mold surface temperature inside the mold of 55°C, and the mold was closed.
Molded articles that could be demolded after 25 minutes had the following mechanical property data:

Total density (g/) densified peripheral area 454 Thickness (mm) 2 Density (g/) 600 Core density (g/) 360 After 100,000 cyclic loads with 70% compression/release at 2Hz Water absorption (g) 5 Example 3 (a) Production of NCO group-containing prepolymer Polyhexanediol having an OH value of 56
1,6/butanediol-1,4 (1:1 mol)
1000 parts were dehydrated for 2 hours at 120° C. and 50 mbar in a stirred flask equipped with a stirrer, thermometer and vacuum connection. Subsequently, 1,5-
240 parts of naphthylene diisocyanate were added and the reaction was completed within 10 minutes at 133°C. Then,
It was cooled to 100°C over 1 hour. NCO content 3.9
% and a viscosity of 3200 mPas at 100° C. 1240 parts of a prepolymer containing NCO groups were obtained.

(b) Manufacture of molded articles To manufacture molded articles, 160 g of the prepolymer described in (a) having a temperature of 100°C are mixed with 1.4 parts of water having a temperature of 50°C 1-methyl-4-dimethylaminoethyl. - Mixed vigorously with 3.45 g of a mixture consisting of 0.03 parts of piperazine, 1.4 parts of sodium salt of Turkish red oil (emulsifier) and 1.4 parts of silicone stabilizer L532 (Fa.BP). After homogenization, the reactive mixture was poured into an aluminum mold with internal dimensions of 21.2 x 5.5 x 3.0 cm, with a mold surface temperature inside the mold of 52°C, and the mold was closed.
Molded articles that could be demolded after 20 minutes had the following mechanical property data:

Total density (g/) densified peripheral area 453 Thickness (mm) 3 Density (g/) 700 Core density (g/) 300 After 100,000 cyclic loads with 60% compression/release at 2Hz Water absorption amount (g) 5 Example 4 (a) Production of NCO group-containing prepolymer Polytetrahydrofuran having an OH value of 112
1000 parts were dehydrated for 2 hours at 120° C. and 50 mbar in a stirred flask equipped with a stirrer, thermometer and vacuum connection. Subsequently, 1,5-
360 parts of naphthylene diisocyanate were added and the reaction was completed within 20 minutes at 130°C. Then,
It was cooled to 100°C over 1 hour. NCO content 4.1
% and a viscosity of 2500 mPas at 90° C. 1300 parts of a prepolymer containing NCO groups were obtained.

(b) Production of the molded article To produce the molded article, 160 g of the prepolymer described in (a) with a temperature of 90°C are mixed with 1.4 parts of water with a temperature of 55°C 0.05 part of pentamethyl-diethylenetriamine 3.45 g of a mixture consisting of 1.4 parts (manufactured by S.A.) were mixed vigorously. After homogenization, the reactive mixture was poured into an aluminum mold with internal dimensions of 21.2 x 3.0 cm, with a mold surface temperature inside the mold of 56°C, and the mold was closed. Molded articles that could be demolded after 30 minutes had the following mechanical property data:

Total density (g/) densified peripheral area 454 Thickness (mm) 3 Density (g/) 700 Core density (g/) 300 After 100,000 cyclic loads of 60% compression/release at 2Hz Water absorption amount (g) 3

Claims (1)

[Scope of Claims] 1. A method for producing a polyurethane molded article having a highly densified peripheral region and substantially closed cells by reacting an organic polyisocyanate, a polyol, and water, comprising: (a) based on organic diisocyanates and substantially linear polyester-polyols or polytetramethylene ether-glycols,
100 parts by weight of an NCO group-containing prepolymer having an NCO content of 3 to 6% by weight and (b) 0.5 to 1.6 parts by weight of water, (c) at least one catalyst and (d) the presence of auxiliaries and optionally additives. Mix vigorously and reduce the resulting mixture to 50
A process for producing closed-cell polyurethane molded articles with a densified peripheral region, characterized in that they are placed in a molding machine with a surface temperature of the inner wall of the mold of ~70°C and cured under compression in a closed molding machine. 2 In order to produce a prepolymer, the OH value is 20~
using a polyester-diol with 225,
A manufacturing method according to claim 1. 3. The manufacturing method according to claim 1, wherein 1,5-naphthylene diisocyanate is used as the organic diisocyanate. 4. The production method according to claim 1, which uses a tertiary amine as a catalyst. 5 Tertiary amine with NCO group-containing prepolymer 100
5. The method according to claim 4, wherein the amount is 0.01 to 2 parts by weight per part by weight. 6. The manufacturing method according to claim 1, wherein the polyurethane molded product has a density of 250 to 800 g/. 7. The manufacturing method according to claim 1, wherein the polyurethane molded product is an elastic member.